This is the first book in C.S. Lewis's amazing Space Trilogy. These books are far less known than Lewis's Narnia series or even his Mere Christianity or The Screwtape Letters, yet it is just as good as any of those writings and goes to show the versatility of Lewis as an author.
This first book begins with our hero, Dr. Ransom, out for a walking tour in the countryside, dressed in that shabby way for which professors are renowned. His foes are his former schoolmates Devine and Weston. These men believe they need a human sacrifice, and by capturing Ransom they have their victim, for they have made a spaceship and are taking Ransom to Malacandra the red planet.
Once on Mars, Ransom escapes his captors, meets many species, and finds out that on Mars there has been no "fall" and Ransom from Earth or the Silent Planet is a bit of an oddity. People from earth are considered to be "bent" in nature, from the original sin of the fall.
Follow Ransom as he treks across a strange world, and must find the courage to risk it all to save not only an alien race, but also, possibly his own soul.
This is a first book in an amazing series. Try it - you won't be disappointed.